181938389 has 2 divisors, whose sum is σ = 181938390. Its totient is φ = 181938388.

The previous prime is 181938377. The next prime is 181938397. The reversal of 181938389 is 983839181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 161163025 + 20775364 = 12695^2 + 4558^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-181938389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181932389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90969194 + 90969195.

It is an arithmetic number, because the mean of its divisors is an integer number (90969195).

Almost surely, 2^181938389 is an apocalyptic number.

It is an amenable number.

181938389 is a deficient number, since it is larger than the sum of its proper divisors (1).

181938389 is an equidigital number, since it uses as much as digits as its factorization.

181938389 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 373248, while the sum is 50.

The square root of 181938389 is about 13488.4539143669. The cubic root of 181938389 is about 566.6411562141.

The spelling of 181938389 in words is "one hundred eighty-one million, nine hundred thirty-eight thousand, three hundred eighty-nine".